The present invention relates to a system for monitoring a vehicle during a crisis situation. More particularly, the invention relates to such a system which may facilitate the efforts of law enforcement personnel and the like to address the crisis situation.
Crimes involving motor vehicles are often bold and violent in nature. For example, in a "carjacking" situation, the assailant will forcibly enter the vehicle while the driver and any passengers are inside. Often, the assailant will then direct the driver to set the vehicle in motion under threat of physical harm. When this occurs, the vehicle may, in a matter of minutes, be many miles from the location of the original forced entry. Therefore, even if law enforcement personnel have been informed that the carjacking has taken place, they may be unaware of the current location of the vehicle. As such, it may be very difficult for them to effectively respond to the incident.
Various vehicle alarm systems have been provided in the past. Generally, such systems are concerned with preventing theft of the vehicle while it is parked. Often, this is accomplished by sounding a loud horn or other audible device when the attempted theft is detected. Examples of prior art vehicle alarm systems are shown in the following U.S. Pat. Nos.: 3,646,515 to Vodehnal, 3,553,641 to Moragne, 3,439,771 to Commins and 3,242,460 to Morrell. The vehicle alarm systems disclosed in each of these patents would be inadequate to address a crisis situation such as that described above.
U.S. Pat. No. 4,067,411 to Conley et al. discloses a vehicle emergency alarm and stop system. This system includes a concealed switch which, when actuated, causes transmission of an emergency condition message to a receiver located at a central station. A coded message may then be transmitted back to the vehicle so that it will be involuntarily retarded or stopped. A portable transmitter is also provided which can be carried by an authorized operator to remotely cause transmission of the emergency condition message. A microphone is also included to allow transmission of conversations occurring in the vehicle.
While the system disclosed in Conley et al. may offer some utility in a crisis situation, it suffers from a number of significant disadvantages. For example, it discloses no means to indicate the location of an affected vehicle. As a result, it may be very difficult for law enforcement personnel to quickly find the vehicle. Additionally, movement of the vehicle under duress can easily cause the range of the vehicle transmitter to be exceeded.
Various systems and devices have also been proposed to monitor the location of vehicles without regard to the problems raised by a crisis situation. One such system is disclosed in U.S. Pat. No. 4,112,421 to Freeny, Jr. In this system, a plurality of signpost units are placed at selected locations in a region which may be traveled by the vehicle. The respective signpost units emit a coded signal which is received by a vehicle unit. The strength of the coded signal can be used to determine whether the vehicle is within the near field or far field region. Adjacent signpost units broadcast distinguishable signals which can be used to determine that the vehicle is within an overlap region between the signals emitted by each. It can thus be seen that the ability of the system of Freeny, Jr. to locate the vehicle is generally dependent upon the spacing of the signpost units. Other prior art monitoring systems, of which the system of Freeny, Jr. is stated to be an improvement, are discussed generally therein.